AK5578 Datasheet, PDF (31/70 Pages) Asahi Kasei Microsystems – 8-Channel Differential 32-bit ADC

[AK5578]
12. Functional Descriptions
■ Digital Core Power Supply
The digital core of the AK5578 is operates off of a 1.8 V power supply. Normally, this voltage is generated
by the internal LDO from TVDD (3.3 V) for digital interface. The internal LDO will be powered up by
setting the LDOE pin = “H”. Set the LDOE pin to “L” and supply a 1.8 V power to the VDD18 pin externally
when a 1.8 V is used as TVDD.
■ Output Mode
The AK5578 is able to output either PCM or DSD data. The DP pin or DP bit select the output mode. Set
the PW2 pin = PW1 pin = PW0 pin = “L” or RSTN bit = “0” or PW8-1 bits = “0H” to reset all channels when
changing the PCM/DSD mode. The AK5578 outputs data from the SDTO1-4 pins by BICK and LRCK in
PCM mode. DSD data are output from the DSDOL1-4 pins and DSDOR1-4 pins by DCLK in DSD mode.
DP pin DP bit Interface
L
0
PCM
H
1
DSD
Table 1 PCM/DSD Mode Control
■ Master Mode and Slave Mode
The AK5578 requires a master clock (MCLK), an audio serial data clock (BICK) and an output channel
clock (LRCK) in PCM mode. In this case, the LRCK frequency will be the sampling frequency. Both
master and slave modes are available in PCM mode. In master mode, the AK5578 internally generates
BICK and LRCK clocks from MCLK inputs and outputs them from the BICK pin and the LRCK pin. In
slave mode, AK5578 operates in the input MCLK, BICK and LRCK. MCLK must be synchronized with
BICK and LRCK but the phase is not important. The AK5578 is in master mode when the MSN pin = “H”
and in slave mode when the MSN pin = “L”.
The AK5578 requires a master clock (MCLK) in DSD mode. Slave mode is not available in DSD mode,
only master mode is supported.
■ System Clock
[1] PCM mode
The external system clocks, which are required to operate the AK5578, are MCLK, BICK and LRCK in
PCM mode. MCLK frequency is determined based on LRCK frequency, according to the operation mode.
Table 2, Table 3, Table 4 show MCLK frequencies correspond to the normal audio rate. Set the
frequency ratio between Sampling frequency and MCLK by the CKS3-0 pins (Table 5)
All channels must be reset when changing the clock mode or audio interface format by the CKS2-0 pins
(bits), TDM1-0 pins (bits), DIF1-0 pins (bits) and the MSN pin. In parallel control mode, all channels will
be reset by the PDN pin = “L” or PW2-0 pins = “LLL”. In serial control mode, all channels will be reset by
RSTN bit = “0” or PW8-1 bits = “0H”. A stable clock must be supplied after releasing the reset.
The AK5578 integrates a phase detection circuit for LRCK. If the internal timing becomes out of
synchronization in slave mode, the AK5578 is reset automatically and the phase is resynchronized.
The following sequence must be executed when synchronizing multiple AK5578’s. Stop all AK5578’s in
reset status by setting the PDN pin = “L” → “H” after stopping the system clock. Make pin or register
settings while all channels are in reset status. After that, input the same system clock to all AK5578’s.
015016736-E-00
- 31 -
2015/12